1. Field of the Invention
The present invention relates generally to a fan impeller structure, and more particularly to a fan impeller structure in which the airflow conducted into the receiving space is increased to enhance the heat dissipation effect. Moreover, no matter whether the fan impeller structure is clockwise rotated or counterclockwise rotated, the airflow can be conducted into the receiving space without being affected by the rotational direction of the fan impeller structure.
2. Description of the Related Art
Following the rapid development of electronic industries, the performances of all kinds of electronic components have been greatly promoted to have faster and faster processing speed. Also, the internal chipset of an electronic component contains more and more chips. The chips work at high speed and generate high heat at the same time. The heat must be efficiently dissipated outward. Otherwise, the performances of the electronic component will be greatly affected to slow down the processing speed of the electronic component. In some more serious cases, the electronic component may even burn out due to overheating. Therefore, heat dissipation has become a critical issue for all kinds of electronic components. A cooling fan is often used as a heat dissipation device for the electronic components.
A conventional cooling fan includes a hub and blades. Multiple coils and electronic components are received in the hub. The blades extend from the circumference of the hub. The diameter and size of the blades relate to the wind power of the cooling fan. The cooling fan is operated by means of the induction between the coils and the electronic components received in the hub. The coils and electronic components will generate heat in operation. It is an important issue how to dissipate the heat generated by the coils and the electronic components.
FIG. 1A is a perspective view of a conventional fan impeller structure. FIG. 1B is a sectional view of the conventional fan impeller structure. The fan impeller structure 1 includes a circumferential wall section 11 and a top section 12 positioned at a top end of the circumferential wall section 11. The top section 12 is formed with multiple through holes 121 and a central hole 122. A motor set 13 is disposed in the circumferential wall section 11. A shaft rod 14 is fitted in the central hole 122. The motor set 13 includes multiple coils 131 and electronic components 132.
By means of the motor set 13, the fan impeller structure 1 can be rotated around the axis of the shaft rod 14. At this time, the coils 131 and electronic components 132 of the motor set 13 generate heat. After a period of operation, the coils 131 and electronic components 132 tend to damage due to overheating. This will shorten the lifetime of the cooling fan. As aforesaid, the top section 12 of the fan impeller structure 1 is formed with multiple through holes 121. When the fan impeller structure 1 operates, some airflow can be conducted through the through holes 121 to the motor set 13 to lower the temperature thereof. However, the airflow cannot be effectively conducted through the through holes 121 to the motor set 13. Therefore, the heat dissipation effect for the motor set 13 is poor. As a result, the motor set 13 is likely to damage due to overheating. This will shorten the lifetime of the cooling fan. Therefore, the conventional fan impeller structure has the following defects:    1. The airflow cannot be effectively conducted.    2. The heat dissipation effect for the motor set is poor.    3. The motor set is likely to damage due to overheating to shorten the lifetime of the cooling fan.